This looks to be an excellent conference and there is no charge for attending virtually, but the registration ends October 6th. Apologies for this belated announcement!

CONFERENCE ANNOUNCEMENT (online free): "42nd International Conference Dyes in History and Archeology"
October 31 - November 2, 2023
Copenhagen, Denmark
Webpage with links for the program, abstracts and registration (in person and online; OPEN UNTIL OCTOBER 6): https://conferencemanager.events/dyesinhistoryandarchaeology